Question

I feel like I’m using Ruby the wrong way here: I want to generate all possible matches for the regular expression /[0-9A-Za-z]{3}/

I can’t use succ because '999'.succ => '1000' and 'zZz'.succ => 'aaAa'. I’m having trouble using ranges because I can’t seem to union (0..9), ('A'..'Z'), ('a'..'z')

So I wrote:

def alphaNumeric   #range and succ don't cut it for [0-9a-zA-Z]   (0..9).each{|x|yield x.to_s}   ('a'..'z').each{|x|yield x}   ('A'..'Z').each{|x|yield x} end def alphaNumericX3   alphaNumeric{ |a|     alphaNumeric{ |b|       alphaNumeric{ |c|         yield a+b+c       }     }   } end alphaNumericX3.each{|x|p x} 

My question is 2 fold:

Is there a less ugly way, and is there a way where alphaNumericX3 could be defined from the parameters (alphaNumeric, 3)?

PS I’m aware that I could define a new class for range. But thats definitly not shorter. If you can make this next block shorter and clearer than the above block, please do:

class AlphaNum   include Comparable   attr :length   def initialize(s)     @a=s.chars.to_a     @length=@a.length   end   def to_s     @a.to_s   end   def <=>(other)     @a.to_s <=> other.to_s   end   def succ     def inc(x,n)       return AlphaNum.new('0'*(@length+1)) if x<0       case n[x]       when '9'         n[x]='A'       when 'Z'         n[x]='a'       when 'z'         n[x]='0'         return inc(x-1,n)       else         n[x]=n[x].succ       end       return AlphaNum.new(n.to_s)     end     inc(@length-1,@a.clone)   end end # (AlphaNum.new('000')..AlphaNum.new('zzz')).each{|x|p x} #  === alphaNumericX3.each{|x|p x} 

Answer 1

Use Array#product:

alpha_numerics = ('0'..'9').to_a + ('a'..'z').to_a + ('A'..'Z').to_a alpha_numerics   .product(alpha_numerics, alpha_numerics)   .map { |triplet| triplet.join('') }